Rotary apparatus for performing a variety of functions on continuous strip material such as strip steel, have been proposed over the last at least fifty years. However, a need has remained for a rotary apparatus to satisfactorily perform precise functions on a moving strip. There are necessarily upper and lower rotary devices which register with one another and they carry respective upper and lower rotary dies. It is well known in all die forming operations that the two dies must register precisely with one another on opposite sides of the workpiece before they close. It is for this that most of the earlier proposals have not been successful. No way was known to achieve a satisfactory form of precise registration of each pair of dies.
However, in U.S. Pat. No. 5,040,397 of Ernest R. Bodnar, Rotary Apparatus granted Aug. 20, 1991, there is shown a form of rotary apparatus, in which upper and lower rotary devices carried semi-rotary die carriers. The die carriers were themselves guided by guide pins. The guide pins rode in cam tracks. The guide pins were located in pairs, one at each end, of each of the semi-rotary devices, and the guide cams were located at opposite ends of the rotary devices.
By offsetting one of the guide pins at one end relative to the guide pin at the other end, and also by precisely profiling the guide cams at each end of each of the rotary devices, it was possible to bring the semi-rotary die supports into precise registration just prior to closing, and during closing, and just after closing on the workpiece. This proposal has proved to be satisfactory for many applications. An improvement to the above described apparatus of U.S. Pat. No. 5,040,397 is described in Canadian Patent Application No. 2,066,803. In that patent application, the inventor, Ernest R. Bodnar, describes the provision of guide pins on each of the semi-rotary die supports. By offsetting respective forward and rearward guide pins on respective guide supports, and by providing two separate guide cams at each end of the rotary apparatus, it then became possible to provide for all four pins to engage respective guide cams just prior to closing, during closing, and just after closing. This proposal may produce a much improved degree of registration between the respective dies carried on the die support. This is particularly important in heavier duty applications, or in applications where the line speed was desired to be increased. Even in this system however there were limitations. For example, it will be understood from a simple geometrical analysis that whereas two dies may register with one another just prior to closing, and during closing and after closing, they are in fact traversing arcs of a circle, as the rotary supports rotate.
This means that the linear speed of the die was greatest at the point where the two dies closed, and was somewhat reduced just prior to closing and just after closing.
On the other hand, since the dies are required to perform operations on a flat workpiece, whether a continuous strip, or discontinuous strip pieces, it will be apparent that there is a very slight degree of "mismatch" in speed of forward movement as between the pair of dies, and the workpiece between them just before closing and just after closing. Precise speed matching is achieved only at the point where the dies are fully closed on the workpiece and the planes of the two dies are precisely tangential to each other.
In operations where relatively thin workpieces were being treated, or where relatively shallow formations were being formed, this slight degree of mismatch in speed did not produce any serious consequences. However, it is desirable to apply this technology to a wider range of products. It is desirable to apply this technology to products having a greater physical thickness than relatively thin sheet metal workpieces, and it is also desirable to apply this technology to the drawing of deeper formations in the workpiece.
In both of these cases, it is apparent that the contact time period during which the two dies are in contact with the workpiece will be somewhat increased as compared to working on thin sheet workpieces such as thin sheet metal and/or drawing relatively shallow formations. In these cases, any degree of mismatch in linear speed between the workpiece itself, and the two dies becomes much more significant.
Accordingly, it is desirable to provide in the first place a method of accommodating the mismatch in speed occurring between the dies moving around a rotary arc, and the workpiece moving along a linear path.
A further problem however relates to the design of the rotary apparatus itself.
In the above noted U.S. patent, and the development thereof described above, herein termed the "two pin rotary", and the "four pin rotary" respectively, the circumferential path around which the die itself could pass was determined by the circumferential path around which the semi-rotary die supports themselves could pass. This meant that if it was desired to increase the size and particularly the depth, of the dies, the entire design of the rotary apparatus had to be redesigned to accommodate these variations.
This clearly either limited the degree of application of the rotary apparatus or meant that considerable engineering costs were incurred each time the rotary apparatus was designed to handle a particular size and depth of die.
Clearly, it is desirable for a more or less standard size of rotary apparatus to be arranged so as to accommodate dies which are themselves of different sizes and in particular in which the dies are of different depths, without being obliged to re-engineer the entire rotary apparatus itself desirably, all that will be required is to place the rotary support devices on centres which are further apart for deeper dies or closer together for shallower dies, and of course, to alter the size and pitch of the gears which interconnect them to ensure that they rotate in unison. This itself is a relatively much simpler task than re-engineering the whole of each pair of the rotary devices themselves.
For the purposes of this application, the term "forming" is deemed to incorporate by reference any die operation which may be performed on a workpiece, whether it may be termed in the trade as "embossing" "forming" "drawing" "blanking" "cutting", or any other operation on a workpiece which is performed by a pair of dies, and wherever used herein the term forming is deemed to incorporate any and all such operations, including those not specifically mentioned above.